Testing hermetically closed cores for mercury boilers



Aug. 6, 1935. B, L. NEWKIRK TESTING HERMETICALLY CLOSED CORES FORMERCURY BOILERS Filed Dec. 29, 1932 De 66c tor Inventor: Burt L Newkirk,y

His Attorn 6y Patented Aug. 6, 1935 I V N IT M AT PATENT TESTINGHERMETICALLY CLOSED COBES FOR MERCURY BOILERS Burt Ll Newkii-k,Schenectady, N. Y., assignor to' 'Gencral Electric. Company, acorporation of ew Y rk I Application December 29; 1932,SerialNo.'649,353

4 Claims. (01. 73 -51 The present invention relates to testing herasubstance which can easily be detected in case I metically closed coresforming a part of the fluid the core leaks.* In manufacturing a core ofthe heating and circulating tubes for mercury boiltype above described Iprovide a substance, prefer erably a volatile substance, in the space ofthe 5 The object of the invention is to provide an core prior to thesealing or closing of the core 5 improved method of testing ahermetically closed and test the sealed core to find out whether anycore to insure complete air-tightness thereof. leakage of the substancethrough the walls of the For a consideration of what I believe to benovcore takes place. el and my invention, attention is directed to theIn Fig. 1 a substance 25, such as mercury, is

following description and the claims appended shown within the space ofthe core. The sub- 10 thereto in connection with the accompanying stanceis placed in the core before the annular drawing which forms a part ofmy specificamember 26 at the upper end of the core is welded tion.thereto.

In the drawing Fig. 1 shows an arrangement In Fig. 2 I have shown anarrangement for for heating and circulating fluid in a mercury testing acore for leakage. The core I4 is placed 15 boiler, and Fig. 2 showsdiagrammatically a part into a chamber 21. Connected to this chamber byof the structure while being tested in accordance means of conduits 28and 29 is an apparatus or with my invention. detector sensitive to vaporescaping from the The structure comprises a drum' In for conhermeticallyclosed space of the core. If mergo taining liquid to be evaporated. Abaffle plate II cury is used as a testing or leakage-indicating isarranged in the interior of the drum in spaced substance for the core Imay use a detecting relation to the lower wall of the drum. Conapparatussuch as that described in the copendnected to the drum is a fluidheating and circuing application, Serial No. 642,895 of C. W. Hewlatingtube which comprises an outer or main lett, filed Nov. 16, 1932. a

25 tube I2 welded to the drum as shown at I3 and. In many cases a coreis fluid-tight at room tem- 25 a core I4 having an inner passage I5 anddeperature but may leak at its operating temperafining with the outertube a passage I6. The ture which is in the order of 1000 F. For thiscore is made of an outer and an inner tubular reason it is preferable totest the core at its member I! and I8 respectively welded togetherintended operating temperature. This may be at their upper and lowerends as indicated at I9 accomplished by providing a heating means such30 and 20 respectively. A tubular'member 2| fasas an electric heatingelement 30 in the test tened to the baflle plate by a weld 22 serves forchamber. During testing the core is heated conducting liquid from thespace above the baiile preferably to its operating temperature. Theplate to the passage I5. This liquid is heated air or like gas containedin the test chamber is and partly evaporated in the space or passagethen circulated through the detector by means of 35 I6 defined betweenthe core and the outer tube a pump forming a part of said detector, theair and returned to the drum. The drum iscovered or like gaseoussubstance filling the chamber on its outer surface with lagging 23 heldin posibeing conducted through conduit 29 to the detion by a cover 24.The structure is more fully tector and discharged therefrom throughconduit 40 described in the copending application of Coulson, 28 to thechamber. If the core leaks, vapor of 40 Serial No. 478,399, filed Aug.28, 1930. the mercury contained in the core mixes with The presentapplication relates specifically to the air or gas in the chamber and iscirculated the core I4 of the tube which as above described through thedetector where it is detected. serves to define a passage I5 for theliquid and a With my invention I have accomplished a passage is for theliquid and e'vapor. Another simple and reliable method'of testinghermetically 45 important function of the tube is to provide a closedstructures, particularly the cores of the means of low heat conductivitybetween the two liquid heating and evaporating tubes for mercurypassages I5 and I6. For proper operation of boilers, mercury boilers itis necessary to cause a rap d What I claim as new and desire to secureby circulation of fluid in the fluid-heating and cir- Letters Patent ofthe United States is,- 50 culating tubes. The rate of circulation is afunc- 1, I th manufacture of mercury boilers tion of the drop intemperature between the fluid prising a tube having a core which definesa space in the down-passage I5 and the fluid in the uphermeticallyclosed by welding, the method of passage It. To minimize the amount ofheat ditesting the cores for leakage comprising insertrectly transmittedfrom passage I6 to passage ing a small amount of mercury into the space55 I5 3. double-walled core is provided which is of the core prior tothe sealing of the core, and hermetically closed and filled with asubstance placing the sealed core into a closed chamber such as air oflow heat conductivity. connected to an apparatus for indicating mercuryIn accordance with my invention I provide in vapor escaping from thehermetically closed space 66 the hermetically closed space defined bythe core of the core, said chamber being heated to a temperature of theorder of the normal operating temperature of the core.

2. In the manufacture of mercury boilers comprising a tube having a corewhich defines a space hermetically closed by welding, the method oftesting the cores for leakage comprising placing a small amount of asubstance into the space of the core prior to the sealing of the core,placing the sealed core into a closed chamber. connected to a detectorfor such substance, and heating the core to its intended operatingtemperature to cause evaporation of said substance for detecting anysubstance escaping at the operating temperature from the hermeticallyclosed spacegof the core. I

3; apparatus for testing adevice of the type described forming ahermetically closed space containing a volatile substance, saidapparatus comprising a hermetically closed chamber, means for heatingthe chamber and a conduit including a detector connected to the chamberfor detecting gases escaping from the device to be tested, said conduithaving one end connected to a lower portion of the chamber and anotherend connected to an upper portion thereof.

4. A core for mercury boiler tubes comprising two substantiallyconcentrically arranged spaced tubular members made of steel, weldsuniting the end portions thereof, and a small amount of mercurycontained in the space defined between the members.

BURT L. NEWKIRK.

